The increasing cost and disposal problems of non-aqueous, oil based functional fluid compositions has accelerated the demand for aqueous based functional fluid compositions. Aqueous based metalworking fluids have been gaining in importance over non-aqueous metalworking fluids because of their economic, environmental and safety advantages. Water based metalworking fluids have been used in chip forming and non-chip forming metalworking processes well known in the art such as drilling, tapping, broaching, grinding, rolling, drawing, spinning, milling, bending, turning and stamping.
Typically, metal working fluids are used in open systems and are exposed to bacteria and other microorganisms. It has been recognized that certain fast growing, easily recognizable bacteria affect fluid performance in use or during extended storage. Use of antimicrobials in aqueous alkaline industrial fluids to reduce the deterioration of fluid performance caused by microbial action on fluid components over time is known in some circumstances.
Due to their comparatively slow growth, other, more resistant, microorganisms, such as Mycobacter have been the focus of less concern. One possible reason for this may be that significant deterioration and hence lowered performance of these industrial fluids by slow-growing organisms is considered relatively unlikely. More recently, it has been proposed that high levels of Mycobacter may be related to respiratory health effects associated with occupational exposure to metal working fluids, including occupational asthma, bronchitis, and hypersensitivity pneumonitis. Wallace, Jr., R. J. et al., “Presence of a Single Genotype of the Newly Described Species Mycobacterium immunogenum in Industrial Metalworking Fluids Associated with Hypersensitivity Pneumonitis”, Applied and Environmental Microbiology, Vol. 68, No. 11, p. 5580-5584, November 2002. Long periods of time between complete changes out of sumps containing recirculating metal working fluids may lead to sizable Mycobacter populations. Significant aerosol levels encountered in certain metal working environments tend to increase the potential for worker exposure.
In some situations, formalin or compounds evolving formalin or formaldehyde have been used to reduce bacterial populations. Elevated working temperatures experienced in some metal working processes may lead to substantial volatilization of formalin or formaldehyde or breakdown of formalin precursors, requiring routine reintroduction of these compounds into the working fluid. In addition, in open systems, and in particular those systems that generate aerosols, such as metal working environments, formalin raises its own environmental and health-related concerns for worker exposure. Another drawback of these formaldehyde-related systems is that they appear ineffective against opportunistic microorganisms such as Mycobacter. 
A limited number of other antimicrobials such as chlorinated phenols, isothiazolinones and dicyclohexylamine have been found to have some efficacy against Mycobacteria in certain situations. Their utilization in metal working fluid operations and environments is hampered by drawbacks in the areas of worker safety, wastewater management, or stability. For example, chlorinated phenols are highly regulated by the EPA in waste streams. Isothiazolinones are expensive, sensitizing agents to tissue, and are not stable in alkaline environments. Pure dicyclohexylamine is toxic by ingestion and absorption and corrosive to the respiratory system.
As a means of extending fluid life and performance, certain secondary alkanolamines have been employed as antimicrobial agents to reduce component deterioration by Pseudomonas or Fusarium species. R. Skold and P. Raune, U.S. Pat. No. 5,633,222; L. Edebo and M. Sandin, U.S. Pat. No. 5,132,046. Certain antimicrobial lubricants that include an alkyl ether amine component have found use in food or beverage container conveyor systems. It has been proposed that these lubricants are useful in reducing slime formation caused by microbial action on food residues, thus improving conveyor performance. Hei, et al. U.S. Pat. No. 5,863,874; Hei, et al. U.S. Pat. No. 5,723,418; and Hei et al. U.S. Pat. No. 5,932,526.
The extent of broad spectrum antimicrobial activity and the level of efficacy for the general class of ether amines appear unpredictable. Hei, et al., U.S. Pat. No. 5,863,874, and Li, et al. U.S. Pat. No. 6,214,777, each disclose lubricating compositions which may include an ether amine for use in conveyor systems where external stresses, such as working temperature or working pressure, are minimal. In Hei, et al. (‘874’), certain ether amines have ascertainable activity against some microorganisms under certain conditions. Under similar working conditions Li et al. discloses certain ether amines at much increased loadings which require a quaternary phosphonium compound as an antimicrobial to achieve the desired effect. External stresses such as elevated temperatures or pressures imposed by the working environment of processes such as metal working may further impact efficacy of certain ether amines through undesired thermal degradation, side reactions, volatilization, and the like. Under working conditions with increased external stresses, it is difficult to predict whether certain ether amines would have broad spectrum activity, a more limited range of activity against some microorganisms, or no activity at all.
There is a need to provide new metal working fluids and methods of their use that inhibit microbial growth including Mycobacteria in metal working fluids as well as metal working environments. There is also a need to provide new metal working fluids that remain effective against Mycobacteria after exposure to workpiece-tool contact zone working pressures of greater than about 60 psi or workpiece-tool contact zone working temperatures of greater than about 50° C. in metal working fluids as well as metal working environments. The present invention is directed to these and other important ends.